Alarm system for refrigerators



June 9, 1964 1.. s. CROSSLEY 3,136,137

ALARM SYSTEM FOR REFRIGERATORS Filed March 8, 1962 p 10 x ii; 53% 1 48 120 I 2 2 52 400 /5O2 BOO 304 4K) 40 4|2 00 f I88 I24 242 IBOL 1;: FIG. 2

INVENTOR. LEO NAR D S. CROSSLEY 3,136,137 Patented June 9, 1964 rCC 3,136,137 ALARM SYSTEM FOR REFRIGERATORS Leonard S. Crossley, Box 66, Manawa, Council Bluffs, Iowa Filed Mar. 8, 1962, Ser. No. 178,320 3 Claims. (Cl. 62-130) This invention relates to alarm systems for refrigerators and particularly for open-top refrigeration units which warm up rapidly on refrigeration failure causing rapid food spoilage.

It is an object to provide an alarm system which will work not only when a refrigeration unit falls during a refrigeration cycle, but also when failure occurs while the unit is in a defrosting cycle.

Alarm systems of the prior art have had no means of coping with a refrigeration unit which develops a failure during the defrosting cycle. It has heretofore been necessary to make alarm systems non-operative during the defrost cycle to prevent false alarms caused not by failure, but by the defrost cycle. This has been the cause of the loss of millions of dollars of merchandise throughout the country.

Ice cream is particularly vulnerable. Within an hour after refrigeration failure of an open, self-service display case, the ice cream is soft. After four or five hours, approximately half the ice cream in a display case will have melted to the point of being unsaleable as quality merchandise. In an overnight failure period, hundreds of dollars worth of ice cream is completely spoiled. Once the water is separated from the solids, any later refreezing crystallizes the ice cream.

The spoilage of meat products in self-service cases is an even greater economic problem. I The managers of grocery stores have a high responsibility in checking this refrigeration equipment. The aid they receive from failure alarm systems of the prior art has not been sufficient because these failures often cause hundreds of dollars worth of damage before they are discovered even during daylight hours. The losses at night are far greater.

It is necessary for a grocery store manager to leave his home on weekends and holidays in order to go to the store to check on the refrigeration equipment.

One might ask why these stores do not install remote alarm systems operating through the telephone circuits. Indeed these have been proposed. However, these systems have operated only during normal refrigeration cycles and do not operate during the defrosting cycles. This means that the store manager having such a system is still not assured that he will be free from the costly loss of merchandise due to failure during the defrosting cycle. Hence most store managers still personally check up on the system at night and on weekends.

It is, therefore, the primary object of this invention to provide means for making such alarm systems operative during the defrosting cycle without false alarms.

The secondary object of the application is to make this system available for use with remote alarm systems sending an alarm signal through the telephone circuits to the store managers home or other station. In this way, remote alarm systems are thereby made practical, thus saving store managers from the physical and economical dangers of robbery and from the loss of valuable merchandise.

Prior art alarm systems, operative on a defrost cycle without false alarm, have been known. However, these have not been applicable to self-service open-top refrigerators. They have had thermal switches resting against the product to detect rise of temperature.

Prior art systems will not Work for open-top freezers because they will not set olf an alarm rapidly enough. The time element is too slow. If such a prior art system is set for alarm upon a slight temperature rise, then this will also actuate the alarm during defrost.

Other and further objects and advantages of the present invention will be apparent from the following detailed description, drawings and claims, the scope of the invention not being limited to the drawings themselves as the drawings are only for the purpose of illustrating a way in which the principles of this invention can be applied.

Other embodiments of the invention utilizing the same or equivalent principles may be used and structural changes may be made as desired by those skilled in the art without departing from the present invention and the purview of the appended claims.

In the drawings:

FIGURE 1 is a vertical cross-section taken through a common open-top self-service food storage case to which elements of this invention have been added.

FIGURE 2 is a wired diagram showing the alarm system of this invention and elements of a standard food storage case with which it works.

FIGURE 3 is a horizontal section taken along the line 3-3 through a thermal switch bulb and mounting bracket.

Referring to FIGURE 1, we there see a standard opentop refrigerator generally indicated at 10 and having a top opening disposed between the points 12 and 14 for access to food stored in a food compartment 15, which latter is formed by a product case 16, the latter having a bottom wall 20 and forward and rearward walls 22 and 24, the end walls of product case 16 being seen at 30 as can also serve as end walls for the entire se1f-service unit 10, as is common.

In accordance with this invention, an outer housing generally indicated at 40 is provided and surrounds the front, bottom, and rearward sides of the product case 16. The outer housing 40 has a forward wall 48, a bottom wall 50, and a rear wall 52.

At the top end of the rear Wall 52 a generally horizontal bafile wall 60 is connected, the wall 60 extending out and over the top wall of product case 16 to direct a flow of air across the top of the product case from the rearward side to the forward side thereof as indicated by arrows 80.

This air flow is generated by an electric air blower disposed at the forward side of the space between the bottom 50 of outer housing 40 and the bottom 20 of product case 16.

The blower 90 pulls air downwardly in the direction of arrow and blows air rearwardly across the convolutions of a coil of an electrical heating unit.

It will be understood that the convolutions of the coil 120 have heating means therein which can be a resistance wire as best seen in the wiring diagram in FIGURE 2 at 124.

The convolutions of the coil 120 are mounted in a support and are disposed beneath the bottom 20 of the product case 16.

Also mounted in the housing 130 are convolutions of a coil which latter is a cooling coil connected to cooling equipment, not shown, which latter is not illustrated since such is standard equipment of a conventional unit of an open-top refrigerator such as the unit 10.

From the rearward side of the cooling coil 140, the flow of air is rearward in a direction of arrow 160, then upwardly in the direction of the arrow 164 between the walls 24 and 52, as is conventional.

Referring to FIGURE 2, it will be seen that the blower 90 has terminals connectable to a power source and that the resistance wire 124 has terminals 188 connected to a power source, as is conventional.

In accordance with this invention, a first thermal switch generally indicated at 20th, operable during a cooling cycle, has its bulb 2&2 disposed in the path of an flowing from the cooling coil 14'!) in a position such that air flows over the bulb 262 after it flows over the 001i 140.

To accomplish this, the bulb 202 is mounted on a bracket 2% fixed to the bottom wall 5@ of the outer housing 40 so that the bulk 202 is preferably beneath the bottom wall 2% of the product case 16 and above the bottom Wall 50 of the outer housing 40.

A second thermal switch generally indicated at 244) has a control bulb 242 for the purpose of preventing an alarm during the defrosting cycle, the bulb 242 being disposed sufiiciently close to the defrost heater coil 12ft so as to be actuated by the turning on of the defrost heater. This is preferably accomplished by clamping the bulb 242 to a convolution of the heater coil 12%, as best seen in FIGURE 3, by means of a pair of brackets 270 and 272 held together by a bolt 280.

The brackets 270 and 272 are of heat conductive metal or other material so that the bulb 242 is directly responsive to heat in the defrost heater coil 120. In FIGURE 3, the heater coil 120 is illustrated as solid since it can be a solid resistance element rather than the wire 124 within a hollow coil 120.

A third thermal switch generally indicated at 306 has a bulb 304 disposed within the outer housing 49 preferably between therearward wall 52 thereof and the rearward wall 24 of the product case 16 in a position so as to be responsive to the temperature rise in an area in close proximity to the product case 16 to initiate an alarm only when the temperature during the defrost cycle has risen to a dangerous point.

The bulb 304 is preferably mounted on a bracket 316) fixed to the inner side of wall 52.

Referring to FIGURE 2, an audible alarm unit or electrical bell device is indicated at 4th and one terminal thereof is connected by wire 402 to a source of electrical current indicated by plug 410.

The other terminal of the audible alarm unit 40% is connected by a wire 412. The other wire 412 of the audible alarm unit 400 is connected to a terminal of the first thermal switch 200 and the terminal of the thermal switch 200 by a wire 420 to a terminal of the second thermal switch 240. The other terminal of the second thermal switch 240 is connected by a wire 424 to the source of power represented by the plug 410.

It will be seen that'the wires 412, 482, and 424 together with the second switch 240 comprise a first control circuit now generally indicated at 435) connected to the alarm system 400 and to the first switch 2% to actuate the alarm in the event of a temperature rise.

A second control circuit which can be generally indicated by a numeral 450 consists of the second thermal switch 240 and is connected in series with and interrupting the first control circuit 430 so that at times it forms a part thereof, whereby the second thermal switch 24f) opens the first circuit 430 during the defrost cycle to prevent actuating the alarm.

. A third control circuit generally indicated at 5% has a wire 502 connected to the wire 43% and to a terminal of the third thermal switch 399 and has a wire 5% leading from the other terminal of the third thermal switch 300 to connection with the Wire 424.

As thus described, the third control circuit is con nected to the third thermal switch 304) and is connected in parallel to the first circuit 438 so that the third switch 300 sets off the alarm 4% in event of too high a temperature in the area of the product case 16.

It will be seen that the alarm 406 can be disposed at a remote point from the product case 16 by simply making wires 402 and 412 very long.

Also, it will be seen that the alarm unit 400 can be any conventional remote alarm operating through conventional telephone circuits in which case the numeral 4% will serve the purpose of indicating such a conventional alarm system operating through telephone circuits and connected to the unit of this invention by the wires 402 and 412;

From the foregoing description, it is thought to be obvious that an alarm system for refrigerators operative on defrost cycle constructed in accordance with my invention is particularly well adapted for use, by reason of the convenience and facility with which it may be assembled and operated, and it will also be obvious that my invention can be changed and modified without departing from the principles and spirit thereof, and for this reason, I do not wish to be understood as limiting myself to the precise arrangement and formation of the several parts herein shown in carrying out my invention in practice, except as claimed.

I claim:

1. In combination: an open top refrigeration equipment alarm system which is adapted to operate during the defrosting cycle, and refrigeration equipment, said refrigeration equipment comprising: a product case having an open top, an outer housing continuously surrounding and also spaced from the front, back, ends and bottom of said product case, an electric air blower disposed between said case and said housing and arranged to blow air in a direction such that said air flows continuously around said case across its top and down one of its sides, and up the other of its sides whereby the flow of said air defines an air flow path, an electrically controlled defrost heater in said air flow path within said outer housing, a cooling means disposed in said air path in a position such that air flows over said heater before it flows over said cooling means, a first thermal switch operative during the cooling cycle and disposed in said path in a position so that said air flows over said switch after it flows over said coil, a second thermal switch to prevent alarm during the defrost cycle and disposed sufficiently close to the defrost heater so as to be actuated by the turning on of said defrost heater, a third thermal switch disposed within said outer housing in a position so as to be responsive to the temperature rise in an area in close proximity to said case to initiate an alarm only when the temperature during the defrost cycle has risen to a dangerous point, a controllable alarm system, a first control circuit connected to said alarm system and to said first switch to actuate said alarm in event of a temperature rise, a second control circuit connected to said second switch and connected in series to and interrupting said first control circuit so said second switch opens said first circuit during defrost cycle to prevent undesired alarm, a third control circuit connected to said third switch, and connected in parallel to said first circuit so that saidv third switch sets off said alarm in event of too high a temperature in said case area.

2. In combination: a refrigerator having in it a product area, said refrigerator having a controllable cooling means having a cooling surface disposed in cooling relationship with respect to said product area, said refrigerator having a controllable heating means. disposed in a position to cause defrosting of said cooling surface, a first thermal switch means for operating while said cooling means is in operation, said first thermal switch means having a first temperature change sensing element disposed in a position for being affected by atemperature change in said product area, a second thermal switch means to prevent alarm while said heating means is in defrosting operation, said second thermal switch means having a second temperature change sensing element disposed in a position for being affected by temperature change in said product area, a controllable alarm system, a first control circuit interconnecting said alarm system and said' first thermal switch for the actuation of alarm in the event of a temperature rise in said product area, a second control circuit connected to said second switch and connected in series to and interrupting said first control circuit so that said second switch opens said first circuit during defrosting of said refrigerator by operation of said heating means to prevent undesired alarm, said first switch being sutficiently far from said heating means as to not close before said second switch opens said first control circuit.

.3. In combination: a refrigerator having in it a product area, said refrigerator having a controllable cooling means having a cooling surface disposed in cooling relationship with respect to said product area, said refrigerator having a controllable heating means disposed in a position to cause defrosting of said cooling surface, afirst thermal switch means for operating while said cooling means is in operation, said first thermal switch means having a first temperature change sensing element disposed in a position for being alfected by a temperature change in said product area, a second thermal switch means to prevent alarm while said heating means is in defrosting operation, said second thermal switch means having a second temperature change sensing element disposed in a position for being affected by temperature change in said product area, a controllable alarm system, a first control circuit interconnecting said alarm system and said first thermal switch for the actuation of alarm in the event of a temperature rise'in said product area, a second control circuit connected to said second switch and connected in series to and interrupting said first control circuit so that said second switch opens said first circuit during defrosting of said refrigerator by operation of said heating means to prevent undesired alarm, said first switch being sufiiciently far from said heating means as to not close before said second switch opens said first control circuit, a third thermal switch means having a third temperature sensing element disposed in a position for being affected by temperature rise in said product area, a third control circuit connected to said first circuit so that said third switch sets off said alarm in the event of too high temperature rise in said product area. 7

References Cited in the file of this patent UNITED STATES PATENTS 

2. IN COMBINATION: A REFRIGERATOR HAVING IN IT A PRODUCT AREA, SAID REFRIGERATOR HAVING A CONTROLLABLE COOLING MEANS HAVING A COOLING SURFACE DISPOSED IN COOLING RELATIONSHIP WITH RESPECT TO SAID PRODUCT AREA, SAID REFRIGERATOR HAVING A CONTROLLABLE HEATING MEANS DISPOSED IN A POSITION TO CAUSE DEFROSTING OF SAID COOLING SURFACE, A FIRST THERMAL SWITCH MEANS FOR OPERATING WHILE SAID COOLING MEANS IS IN OPERATION, SAID FIRST THERMAL SWITCH MEANS HAVING A FIRST TEMPERATURE CHANGE SENSING ELEMENT DISPOSED IN A POSITION FOR BEING AFFECTED BY A TEMPERATURE CHANGE IN SAID PRODUCT AREA, A SECOND THERMAL SWITCH MEANS TO PREVENT ALARM WHILE SAID HEATING MEANS IS IN DEFROSTING OPERATION, SAID SECOND THERMAL SWITCH MEANS HAVING A SECOND TEMPERATURE CHANGE SENSING ELEMENT DISPOSED IN A POSITION FOR BEING AFFECTED BY TEMPERATURE CHANGE IN SAID PRODUCT AREA, A CONTROLLABLE ALARM SYSTEM, A FIRST CONTROL CIRCUIT INTERCONNECTING SAID ALARM SYSTEM AND SAID FIRST THERMAL SWITCH FOR THE ACTUATION OF ALARM IN THE EVENT OF A TEMPERATURE RISE IN SAID PRODUCT AREA, A SECOND CONTROL CIRCUIT CONNECTED TO SAID SECOND SWITCH AND CONNECTED IN SERIES TO AND INTERRUPTING SAID FIRST CONTROL CIRCUIT SO THAT SAID SECOND SWITCH OPENS SAID FIRST CIRCUIT DURING DEFROSTING OF SAID REFRIGERATOR BY OPERATION OF SAID HEATING MEANS TO PREVENT UNDESIRED ALARM, SAID FIRST SWITCH BEING SUFFICIENTLY FAR FROM SAID HEATING MEANS AS TO NOT CLOSE BEFORE SAID SECOND SWITCH OPENS SAID FIRST CONTROL CIRCUIT. 